In conventional filmmaking etc., to obtain special video effects, scenes have been shot in condition where a shooting speed of a film camera, that is, the number of frames per second has been varied. For example, if a scene is shot at a higher speed than an ordinary one and reproduced at the ordinary speed, reproduced images are slowly seen. Therefore, fast motion of, for example, a water droplet falling into water can be observed easily and in detail. If a scene is shot at a lower speed than the ordinary one and reproduced at the ordinary speed, on the other hand, reproduced images can be fast seen. It is thus possible to enhance a sense of speed in a fight scene, a car chase scene, etc., thereby presenting images with an enhanced sense of reality.
Further, in TV program making etc., while an attempt has been made to digitize processing of shooting, editing, delivery, etc. of a program, an attempt has also been made to digitize processing in filmmaking etc. as fueled by an increase in image quality and a decrease in costs caused by progress in digital technologies.
It is noted that if images are to be picked up using an image pick-up device (video camera) due to digitization of TV program, filmmaking, etc., an image pick-up device described in Jpn. Pat. Appln. KOKAI Publication No. 2000-125210 and supposed to be capable of frame rate-varying is used so that special video effects such as fast reproduction and slow reproduction can be obtained easily. By using this image pick-up device to pick up images at a lower speed than a predetermined frame rate and reproduce them at the predetermined frame rate, fast motion of the reproduced images can be obtained easily. By picking up the images at a higher frame rate and reproducing them at the predetermined frame rate, on the other hand, slow motion of the reproduced images can be obtained easily.
In a case where a plurality of image pick-up devices each capable of varying a frame rate thereof is used to pick up images of a target in different directions, by synchronizing the frames of image signals obtained by these image pick-up devices with each other, it is possible to obtain a fast motion reproduction image or a slow motion reproduction image that has the same speed and has been picked up in the plurality of directions. For example, if the target is shot at a higher frame rate and reproduced at a predetermined frame rate, it is possible to obtain a slow motion reproduction image picked up in different directions in which the target moves at the same speed. Therefore, by synchronizing the frames of the image signals obtained by the image pick-up devices with each other, it is possible to facilitate subsequent editing processing. However, if the frame rates of the image pick-up devices are varied during image pick-up, it is, almost impossible to synchronize the frames of the image pick-up devices through user operations.